1. Field of the Invention
The present invention relates to antennas. More specifically, the present invention relates to high-power, millimeter-wave antennas, systems and components that are portable in general and have solid-state sources in particular.
2. Description of the Related Art
Directed-energy systems have been considered for a variety of applications. In particular, millimeter-wave based systems are receiving ever increasing interest for both commercial and military applications. Millimeter-wave reflect arrays using solid-state power generating circuitry have been constructed and tested. See U.S. Pat. No. 6,765,535 entitled MONOLITHIC MILLIMETER WAVE REFLECT ARRAY SYSTEM, issued Jul. 20, 2004, by K. W. Brown et al. the teachings of which are hereby incorporated herein by reference.
In a reflect array, the losses are minimized by feeding the array elements via free space. Each element is equipped with a transmit and a receive antenna (which may be one and the same). The power received by the receive antenna feeds a power amplifier whose output is injected into the input of the transmit antenna and reradiated. The transmit and receive antennas are usually orthogonally polarized to provide isolation between the transmit and receive paths. These have worked well, but are limited by the need to isolate the transmit and receive paths. To increase per-element power generation requires that the outputs of multiple power amplifiers be combined on-chip, requiring the use of power combiners that consume valuable surface area that might otherwise be occupied by additional power amplifiers. In addition, the need for an external feed structure limits reflect arrays for certain applications.
A transmit array, such as that disclosed and claimed in the above-identified parent application, and quasi-optical power combiners in general address some of the shortcomings associated with reflect arrays. However, the power output of such arrays remains too limited with respect to certain applications.
The conventional approach to millimeter-wave power generation involves the use of transmitters utilizing vacuum electron devices (VEDs) such as gyrotrons or klystrons. There are numerous known shortcomings associated with the use of VEDs. For example, they tend to be heavy and bulky and require high-voltage power supplies. In addition, high-power VEDs have long warm-up and/or cool-down times, are of questionable reliability, and are fragile. Hence, high-power VED based systems are not easily portable, and are expensive and too fragile for many applications. Further, these devices are typically not scaleable.
Hence, a need remains in the art for an improved system or method for generating and directing high-power millimeter-wave energy.